/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.transforms.windowing;



import org.joda.time.Instant;



import java.util.Arrays;

import java.util.List;



/**

 * A {@link Trigger} that fires according to its subtrigger forever.

 *

 * <p>For example, to fire after the end of the window, and every time late data arrives:

 *

 * <pre>{@code

 * Repeatedly.forever(AfterWatermark.pastEndOfWindow());

 * }</pre>

 *

 * <p>{@code Repeatedly.forever(someTrigger)} behaves like an infinite {@code

 * AfterEach.inOrder(someTrigger, someTrigger, someTrigger, ...)}.

 *

 * <p>You can use {@link #orFinally(OnceTrigger)} to let another trigger interrupt the repetition.

 */

public class Repeatedly extends Trigger {



  private static final int REPEATED = 0;



  /**

   * Create a composite trigger that repeatedly executes the trigger {@code repeated}, firing each

   * time it fires and ignoring any indications to finish.

   *

   * <p>Unless used with {@link Trigger#orFinally} the composite trigger will never finish.

   *

   * @param repeated the trigger to execute repeatedly.

   */

  public static Repeatedly forever(Trigger repeated) {

    return new Repeatedly(repeated);

  }



  private Trigger repeatedTrigger;



  private Repeatedly(Trigger repeatedTrigger) {

    super(Arrays.asList(repeatedTrigger));

    this.repeatedTrigger = repeatedTrigger;

  }



  public Trigger getRepeatedTrigger() {

    return repeatedTrigger;

  }



  @Override

  public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) {

    // This trigger fires once the repeated trigger fires.

    return subTriggers.get(REPEATED).getWatermarkThatGuaranteesFiring(window);

  }



  @Override

  protected Trigger getContinuationTrigger(List<Trigger> continuationTriggers) {

    return new Repeatedly(continuationTriggers.get(REPEATED));

  }



  @Override

  public String toString() {

    return String.format("Repeatedly.forever(%s)", subTriggers.get(REPEATED));

  }

}